First, check the crown or bridge to see if it's in one piece. If it is, place a thin coat of petroleum jelly inside the crown or bridge. Then, carefully press it back in place. It is important to keep the teeth in their proper position by replacing the crown or bridge immediately. Do not chew on the replaced crown or bridges as it may come off again. This is only a temporary solution. Be sure to call your dentist as soon as you can to have the crown or bridge examined and re-cemented.